Temperature dependence of the electrical properties of organic thin-film transistors based on tetraphenyldibenzoperiflanthene deposited at different substrate temperatures: Experiment and modeling

摘要

A series of inverted-staggered (top contact) p-channel organic thin film transistors based on small molecule tetraphenyldibenzoperiflanthene (DBP) as an active layer have been fabricated by thermal evaporation at different substrate temperatures (300, 330, 360 and 390 K). In this work, these devices have been electrically characterized at different temperatures from 300 K to 370 K in steps of 10 K under vacuum. The influences of the temperature on the electrical performance of DBP-TFTs have been investigated in saturation regime. We found that the p-channel DBP-TFTs deposited at a substrate temperature (Tsub = 390 K) exhibited a better performance under a measurement temperature of 370 K, where µFET, Vth and the ratio current were approximately 8.5 × 10- 4 cm2 V- 1 s- 1, - 0.33 V and 3 × 106, respectively. The field effect mobility of these types of devices is strongly dependent on temperature and follows the simple Arrhenius law. Additionally, the temperature-dependent electrical measurements performed on these devices reveal a thermally-activated behavior for each substrate temperature. This suggests that the charge transport in the examined devices occurs via hopping between localized states. The obtained results demonstrate well that the deposition conditions of organic active layer can improve well the device performance. Finally, an analytical model has been developed to reproduce the dependence of the total resistance and the current-voltage characteristics with the temperature and to understand the charge transport in the DBP-TFTs. The obtained data are in good agreement with the experimental results for all fabricated devices.